Method of cracking hydrocarbon oils



F. T. MANLEY. METHOD 0F cRAcKlNG HYDRocARBoN ons.

APFLICATION FILED OCU-101.1917.

Patented Sept. f',

kohvellwm.

Patented Sept. 5, 1922.

UNITED STATES PATENT OFFICE. l

FREDERICK T.

MANLEY, OF HOUSTON, TEXAs, AssIGNOE To THE TEXAS COMPANY,

OF NEW YORK, N. Y., A CORPORATION OF TEXAS.

METHOD 0F CRACKING HYDROCARBON lOILS.

Application lfiled October 10, 1917. Serial No. 195,777.

cracking of such oils' as kerosene, gas oil,

lubricating Oil and the like, for the production of more volatile products, such as are usually designated by such terms as naphtha and gasoline.

In the practice of cracking hydrocarbons for the roduction of these volatile products one di culty commonly encountered is the construction and maintenance of apparatus capable of withstanding the high pressure usually sought to be employed. It is an object of my invention to minimize this dificulty by the use of suitable heating means whereby a sufficient 4heat may be maintained in. the cracking zone to effect the desired decomposition with a reduction of the usual pressures. It is a further object of my invention to. provide a heating zone capable of a combined liquid-vapor phase cracking process and of such a character that there is no local superheating with. the consequent.

largeproduction of fixed gas and carbon.' In general this invention preferably contemplates passing a lower-boiling hydrocarbon through a still charged with a higher-boiling hydrocarbon and heated to a high-temperature, and collecting the resulting vapors of desired volatility. Icharge a suitable still with one of the higher-boiling hydrocarbons, such as a residuum or one of the heavier distlllates I of petroleum distillation. I heat the higherboiling oil and then introduce into the still the lower-boiling hydrocarbon, such as a gas Oil' or kerosene distillate. The heat in the still vaporizes and cracks the lower-boiling oil and the vaporized and cracked products tend to gather in and pass along the vapor ortion of the still where there is maintained a heat suiiicient to further decompose the vaporized constituents into morey volatile products., The conversion therefore takes place in a combined liquid-vapor phase By reason of the presence in the still of the higher-boiling oil it is possible to maintain a temperature suiicient to vaporize and decompose the lower-boiling Oil -without using the excessive pressures which would otherwise required to obtain the desired decom Os1t1on.

yprocess may be carried out by any suitable means. A form of apparatus by whlch the herein disclosed process maybe successfully operated is illustrated in the accompanying drawing. v

For the purpose of fully explaining my process yI will describe 4herein the method pursued when usin the apparatus illustrated, but ity is to e understood that the use of my process is not confined to said apparatus.

In the drawings:

Figure 1 is a vertical longitudinal. section through the device;

Fi a modified construction showing` Scrapers 1n the cracking still; and

Figure 3 is an end view.

Referring to the drawing, a cracking still 4, preferably of considerable length in comparison with its diameter, is placed horizontally in a furnace 1, having burner 2, baffle wall 3 and stack 13. still 4 is supported by the wallsof the furnace and by T irons 9. At one end of .the still 4 is a vapor line 5 extending to an air condenser 6. From the lower p-art of the air condenser extends a conduit 7 to the other end of the cracking still. A supply pipe 12 enters the tube preferably at one end thereof. 8 is a draw-Off pipe. 17 and 18 denote recording thermometers, and 19 and 2O designate `furnace pyrometers. 16 is a pressure gauge. y

The heating arrangement of the furnace is such` thatl the hot combustion gases are deliected by the baiiie 3 to the rear ofthe furnace where they enterthe heating cha1nber containing the cracking still 4. The hot gases pass along the still imparting heat to the entire periphery thereof, andfi'nd exit through the stack 13. The still 4 is provided with an insulated plate 22 which prevents any local overheating which might otherwise Occur along that portion of the still near where the furnace gases enter the heating chamber. The upper periphery of the still is covered with a light insulation 21 which enable not only the maintenance of gure 2 is an. enlarged section through y I a high degree of heat in the vapor zone of the still, but a heated zone of even temper with no local overheating.

l preferably charge the still 4 with a residuum or one of the heavier distillates of petroleum distillation through pipe 30 until it is partially filled and heat the still until there is generated therein the desired cracking temperature, which is ordinarily from 650 to 800o F., the exact temperature, of course, depending upon the character of the hydrocarbons used in the operation. When the desired temperature is obtained l introduce, through the supply pipe 12, the lowerboiling hydrocarbon, such as a gas oil or kerosene distillate. The lower-boiling hydrocarbon on coming in Contact with the highly heated hydrocarbon body in the still 4 is partially cracked in the liquid phase and part1ally vaporized and decomposed in the vapor phase. As it passes along the eX- tended cracking still the vaporized and cracked constituents tend to gather in the vapor zone along the upper portion of still 4 above the heavy oil where there is maintained a sufficient heat to further decompose the vaporizedconstituents into more volatile products. The generated vapors pass out of the cracking still through the vapor conduit 5 to the air condenser 6 from which the gasoline or naphtha constituentsv are conducted by the pipe 15 to the water condenser 28 provided with outlet valve 29 by which the pressure in the apparatus may be controlled. The less volatile constituents in the air condenser 6 are returned to the cracking still by the conduit 7 and are forced through the cracking still by the injector effect of' the ingoing oil which is continuously charged into the cracking still through pipe 12. The gasoline or naphtha constituents are continuously passing through the Vapor line and separator into the water condenser and are withdrawn continuously from the outlet 29.

ll also maintain the supply of the higher boiling oil in still 4 by continuously or intermittently-feeding such oil in through pipe 30. The vaporized products which pass to the air condenser 6 and which are not of y sufficient volatility for the gasoline or naphtha desired,`are continuously condensed therein and returned to the still and repass through the extended and combined liquid vapor cracking zone.

a more specific example of my process ll may use as the higher boiling oil a residuum having a gravity of 26 Baume, a

dash point of 265 and a distillating point of 445 `(as tested in the ordinary Engler distilling flask). ll charge the still 4 with this residuum and apply heat thereto until dis-A tillation begins, the temperature of the oil at this point being 700 F., as denoted by the thermometer 18. rllhe lower boiling oil,

rasees@ which may be a distillate from which all of the light products, such as gasoline of naphtha, have been removed, and which has a Baum gravity of 39, a flash point of 190 and a distilling point of 354, is then introduced into the still. The valve controlled outlet 29 is so regulated that a suiicient pressure is constantly maintained on the apparatus. The distillate on coming in contact with the highly heated body of oil under this pressure is partially decomposed and partially vaporised and then decomposed. rlllhe distillate is continuously supplied to the still and from time to time fresh residuum is added. rlhe residue formed, containing carbon and asphaltic bodies, is drawn oi through the outlet 8.

rllhe cracking still 4 may be provided with rotary means for removing any carbon or other deposit on the interior surface of the still, the rotary scraping means being mounted and arranged substantially as disclosed in my co-pending application, Serial Number 195,774 liled of even date herewith. rlhe scraping means is shown in Figure 2, Where the rotary shaft 24 extends axially into the still 4 from one end andturns in a bearing in said still at Athe other end. At the entrance end the still 4 is provided with a projecting-'pipe of smaller diameter through which the shaft 24 passes and at the outer end of which there is a st ui'ling box and bearing removed from the polnt of hlgh heat. The shaft 24 carries steel brushes 25 supported on rods 27 and pushed outward by coiled sprin s 26. These brushes are placed only along t at portion of the st1ll 4 recelving the high cracking heat.

lin the operation of the hereln dlsclosed process ll construct the cracking still 4 of` considerable length, as from 25 to 50-feet long. The object of this is to form a heating zone of such extent that the lower-bollmg oil will be heated suiiiciently to thoroughly vaporize and decompose it into volatile constituents and to reduce to a minimum the passage from the cracking still of products less volatile than desired. There is, however, usually a considerable quantity of constituents which, although less volatile than gasoline or naphtha, are yet so readily vaporized that they. tend to pass out from the heating zone sorapidly that they will not be decomposed intrl products of the desired volatility. rlhe decomposition of these products is effected by returning them after condensation to the cracking still through pipe 7 and continuously forcing them' through the extended heating zone.

Without the insulation 21 the vapor portion of the still, by reason of the greater ability of the oil vapors to absorb heat, would attain a temperature considerably higher than the liquid portion, thereby causingA the vapors to be overheated and resultinto a lighter product such as gasoline.

ing in the formation of a product containing a large proportion of unsaturated compounds. By means of the insulation 21, the rate of conduction of heat through the vapor zone is reduced so that both the liquid and the vapor portions are maintained Vat substantially the same temperature, thereby creating a combinedliquid-vapor cracking zone of such a character that while a heat sufficient for decomposition is maintained, it is an even-tempered heat with no local overheating. The hydrocarbons passing through this extended, even tempered, cracking zone are effectually decomposed into products of the desired volatility. v

Attention is directed to the fact that there is a4 time element necessary to the. effective and complete cracking of hydrocarbon oiIls t is consequently desirable to keep the oil such as kerosene or gas oil which is to be c811- verted into gasoline or the like, at a cracking temperature for a considerablel length of time.

This result, according to the process of my present invention, is accomplished by providing an elongated cracking zone through which the kerosene or the like must necessarily pass either in liquid or in vapor form before it can escape into the vapor line.

This long zone is maintained at a substantially -constant temperature by partially filling it, about half full for example, With heavy hydrocarbon residue or the like, which is maintained at a cracking temperature and by insulating the vapor space to prevent the temperature from becoming excessive.

Having thus described the invention what is claimed as new and desired to be secured by Letters Patent is l. .The continuous process of cracking hy` droca-rbon oils of comparatively low boiling points which consists in bringing said oils in contact with a horizontally elongated body of higher boiling point hydrocarbon oil i maintained at a -temperature sufficient to cause vaporization and decomposition of said lower boiling oil, causing the vaporsgenerated to pass along in contact with the Ielongated surface of said heated higher boiling point oil and preventing overheating of said vapors during said passage to maintain a substantially uniform temperature of suffi?v cient intensity to continue the cracking of the vapors.

2. The continuous process of cracking hy` drocarbon oils of comparatively low boiling point which consists in bringing said oils in contact with a horizontally elongated body of higher boiling point hydrocarbon oil maintained at a temperature sufficient to cause vaporization and decomposition of said lower boiling oil, causing the vapors generated to pass along the elongated surface of said heated higher boiling point oil proabove.said liquid body at a substantially` uniform cracking temperature and forcing said comparatively low boiling point oil through the elongated cracking zone,'con

sisting of said liquid body and vapor space and condensing the vapors after they have passed through said zone.

4. The continuous process of cracking hydrocarbon oilsy of comparatively low boiling points, that consists in maintaining a horizontally elongated body of high boiling hydrocarbon'oils at a cracking temperature and maintaining an elongated vapor space above said liquid body at a substantially uniform cracking temperature, introducing at one end said comparatively low boiling point oils into the cracking zone, consisting of said liquid body and vapor space, withdrawing vapors from the opposite end of said zone, separating uncracked oils from said vapors, and returning them to the charging end of the cracking zone.

5. The continuous process of cracking hydro-carbon oils of comparatively low boiling point, which comprises delivering said oils to one end of a horizontally elongated `liquid-vapor cracking zone, maintaining both liquid and -vapor spaces of the cracking zone at a substantially uniform crackthroughout the entire length ofthe cracking zone whereby they are crackedI in a. combined liquid-vapor phase.

6. The continuous process ofl cracking hydro-carbon oils of comparativelylow boiling point, which comprises maintaining' phase, and withdrawing the evolved vapors from the other end of the cracking zone. A 7. The continuous process of cracking hydro-carbon oils of comparatively low boiling point, which comprises subjecting the" liquid and vapor spaces of a horizontally elongated cracking zone to substantially uniform cracking temperatures, passing the oils throughout the entire length of the cracking zone whereby a'portion of the oil is converted in the liquid phase and a poring temperature, and passing the oils i p tion thereof vaporized and converted in the vapor phase, withdrawing the evolved vapors from lthe farther end of the cracking zone, separating out the unconverted portions of the evolved vapor and returning them to the cracking zone for re-treatment.

8. The continuous process of cracking hydro-carbon oils of comparatively low boilingv point, which comprises subjecting to cracking heats the entire periphery of an elongated horizontal cracking still throughout its length, the still being partially filled with oil and'having a vapor space above the level of the oil therein, heatinsulating the vapor space of the still to establish substantially uniform cracking temperatures in the liquid and vapor spaces of the still, introducing the oils to be converted into one end of the still, and withdrawing the evolved vapors from the other Aend thereof, whereby the oils are cracked in a combined liquid-vapor phase in transit through the still.

10. rlhe continuous process of cracking hydro-carbon oils of comparatively low boiling point, which comprises heating an elongated. horizontal still having a vapor space above the level of the oil therein so that both its upper and lower potions are maintained at a substantially uniform cracking temperature, passing the oil to be converted through `the still whereby it is Mascara cracked, partially in the liquid phase and partially in the vapor phase, and creating a cyclic circulation through the cracking zone to cause the unconverted constituents of the vapor evolved to be repassed through the still and repeatedly subjected to cracking conditions. p

10. The continuous process of cracking hydro-carbon oils which consists in passing a lower boiling oil through a cracking zone comprising a lower liquid portion and an upper vapor portion, the liquid portion being composed of a higher boiling oil maintained at a temperature suflicient to decomvpose sa'id lower boiling oil and both liquid and vapor portions being heated externally., the rate of heat conduction to the Vapor portion being less than that to thel liquid portion so that substantially the same temperature is maintained in the vapor and liquid portions o f the cra-cking zone. 1 1. The continuous process of cracking hydro-carbon oil which consists in passing lower boiling oil through a cracking zone comprising a lower liquid portion and an upper vapor portion, and applying heat 'o the cracking zone under such conditions as to maintain a substantially uniform cracking temperature in both the liquid and vapor portions thereof.

lin testimony whereof l alix my signature;

FREDERICK T. MANLEY. 

